While interlocking may be a word in common enough usage, in the past 18 months it has taken on a whole new meaning in the efficiency and operation of kitchen extractor systems and become a key word in health and safety legislation, impacting on any new piece of gas-fired cooking equipment installed in professional kitchens.

The obvious role for kitchen extraction systems is to provide comfort in the working environment by lowering ambient temperature, but its most important function is in removing harmful fumes caused in the burning of gas used to fuel prime cooking equipment.

The two gases which give the Health & Safety Executive (HSE) the greatest concern are carbon monoxide and nitrogen dioxide, both of which can cause short-term and long-term damage to health if absorbed in large amounts.

Until last year it was assumed that the installation of an extraction canopy in the kitchen removed all risk of carbon monoxide poisoning to chefs, but in September much stiffer legislation came into force. The concern was that, should there be a failure in the air movement within the extraction system, typically through fan failure, then deadly carbon monoxide could begin to build up in the kitchen as gas jets blazed away.

Interlocking describes a mechanical link between sensors in the extraction system and the main valve of the gas supply to cooking equipment. Should the carbon monoxide level in the ventilation system go up, then the interlocker will turn off the gas supply at the mains, indicating to the kitchen staff that something has gone wrong.

Any completely new kitchen built after September last year must have interlocking on the ventilation system, and any replacement, new installation or modification to existing ventilation systems must incorporate interlocking. All professional kitchen designers and distributors are aware of this new legislation, so it will have been schemed into the kitchen plan - but it is still worth checking at the design stage.

Where the health and safety legislation on interlocking becomes murky is in replacement of worn gas-fired equipment or the installation of just a single new piece of equipment. Is that considered a new kitchen and therefore subject to the interlocking regulations? If it is, the implication is that by introducing just one new piece of gas-fired equipment in the kitchen, the whole ventilation system will have to be upgraded. It would even apply if a piece of gas-fired equipment was serviced or repaired.

The implications of that, according to Nick Oryino, technical specialist with the Catering Equipment Distributors Association (CEDA), are horrendous. Says Oryino: "It would have cost the industry millions. Our engineers would have been slapping at-risk notices on equipment by the hundred."

The Council for Registered Gas Installers (Corgi), the governing body of anyone who wishes to work with gas appliances, says any gas work done in the kitchen will now mean the installation of interlocking on ventilation systems. CEDA says it won't, and that Corgi is overreacting. Round-table discussions with the HSE have resulted in a compromise whereby an engineer installing a new piece of equipment or doing a repair under an existing ventilation canopy will make a risk assessment of the kitchen and its ventilation and issue a certificate regarding the equipment, to be kept by the kitchen manager as part of normal HACCP management.

If the certificate is marked NCS, that means "not to current standards" and simply indicates that the equipment has been fitted after last year's legislation came into force. An NCS certification is unlikely to have any bearing on kitchen insurance or health and safety procedures. If the certificate says AR, that means "at risk", and it would be unwise and possibly contrary to insurance terms to continue to use the equipment without modifying the ventilation. The most draconian certification is ID, meaning "immediately dangerous", and such equipment must be shut down at once.

A typical example of where an NCS certificate would be issued would be a fast-food restaurant with an efficient and well-maintained ventilation system where an existing fryer had been replaced under an extractor hood without the interlocking safety feature. The engineer would advise that interlocking should be fitted at some point in the near future, but use of the equipment would be unaffected.

Where it becomes a serious problem is in those old, city centre hotels where the kitchen is below ground and spread through a number of small rooms, and the ventilation is old or non-existent. For any chef whose kitchen fits this description, the next time an engineer calls to do a repair or fit a new piece of gas-fired equipment, at best an AR certificate will be issued, saying you have been warned not to use it. More likely, an ID certificate will result, demanding a complete shutdown.

Chemical concerns

A relatively new risk to kitchen staff is from the use of cleaning chemicals. Chefs have always had to do a clean-down at the end of a shift, but traditionally it was with hot, soapy water. The use of harsh chemicals to clean the kitchen and cooking equipment is growing and it brings new health and safety risks.

Steve Gerring, head of safety solutions at kitchen safety consultants Set Solutions, says that while the danger to staff of slips, trips and falls has been addressed, the newer risk of hurt by cleaning chemicals is not always realised. Says Gerring: "Kitchen managers think protective equipment is the answer, but that is the last resort. Think about downgrading the chemical to a less hazardous one. The cleaning activity has to be done, but think about low risk to food and low risk to employees."

Mucky ducts and danger

A build-up of carbon monoxide is not the only health and safety issue surrounding kitchen extraction systems. Failure to keep them clean, so allowing a build-up of grease, can cause spectacular kitchen fires. In many cases the fire is not a smouldering flicker that can be dealt with by kitchen staff, but a flash fire that happens in a split second, setting all the ductwork alight. Even where fire-extinguishing systems are built in to the canopy, the flash fire can be too quick for the sensors to spot and for the retardant to trigger into action.

The annual insurance bill for kitchen fires in the UK is £65m a year and rising. So concerned are insurance underwriters at the safety risk extraction systems carry that, increasingly, policy terms stipulate that failure to clean ductwork regularly could result in an insurance claim not being paid.

Craig Booth, sales director of ventilation says he has seen some unbelievable horrors involving poorly maintained ductwork in both multiple restaurant chains and individual hotels and restaurants. Says Booth: "Out of 80 extraction system inspections made in recent months, over 50% had been inadequately cleaned and could be considered a fire hazard, a health hazard or both."

The time between each cleaning varies according to the volume and type of food being cooked, but in a busy fast-food restaurant with banks of heavy-duty fryers going up to 18 hours a day, the cleaning cycle is measured in days rather than weeks or months.

For more information contact...

CEDA
01274 826056

System Hygienics
01323 849988

Set Solutions
020 7474 6667

Vent Master
01634 666111

Ecosteam
01256 681255